Closure operator

ABSTRACT

A closure operator to effect remote, fail-safe opening and closing of a closure, particularly a multifold or interlocking slat curtain damper. A frame or shell envelopes the damper curtain which is capable of opening and closing an air passage defined by the frame or shell. A rotatable drum is positioned within the frame or shell adjacent the curtain when it is folded so that the drum will not obstruct airflow through the damper when the damper is opened. A cable couples the drum and the curtain; and the curtain is opened in response to the winding of the cable about the drum in response to drum rotation. A drum drive mechanism is axially aligned relative the axis of the drum so that both components extend completely across the frame or shell immediately adjacent the folded curtain. Upon occurrence of (1) a manual switch operation to effect damper closure, (2) a power failure, (3) circuit malfunctioning, or (4) the detection of an undesired condition such as smoke or fire, the drum drive clutch is disengaged. When the clutch is disengaged, the drum unwinds to lower the curtain and close the damper. In an alternative drum embodiment, the drum includes a cable takeup spool and a drum body of relatively greater mass than the spool. A drawn cup roller clutch couples the spool to the drum body. This clutch is engaged when the curtain is folded to open the damper; and the clutch is disengaged when the curtain is released to close the damper. With this drum arrangement the forces of drum momentum acting upon the cable (and tending to rewind the cable in the opposite direction) are substantially minimized when the curtain is released for damper closure.

United States Patent Ellis Mar. 7, 1972 [54] CLOSURE OPERATOR David R. Ellis, West Chicago, Ill.

[73] Assignee: Rixson lnc., Franklin Park, Ill.

[22] Filed: Dec. 22, 1969 [2|] .Appl. No.: 886,916

[72] inventor:

[521 US. CL .38/110, 160/34. 160/84 [SI] Int. Cl ..F24f 13/00 [58] Field ofSearcll....................l60/5, 6, 84, 32, 33, 34, 35,

l60/33l, 311; 25l/DlG. 2; l37/75; 98/110, I21, 86

[56] References Cited UNITED STATES PATENTS 1,894,833 1/1933 Ruby ...160/34 2,320,852 6/1943 De Falco ...l60/84 2,509,033 5/1950 Carver ...160/84 3,294,151 12/1966 Hartley......................................160/5 Primary ExaminerMeyer Perlin AttorneyAugustus G. Douvas [57] ABSTRACT A closure operator to effect remote, fail-safe opening and closing of a closure, particularly a multifold or interlocking slat curtain damper.

A frame or shell envelopes the damper curtain which is capable of opening and closing an air passage defined by the frame or shell. A rotatable drum is positioned within the frame or shell adjacent the curtain when it is folded so that the drum will not obstruct airflow through the damper when the damper is opened. A cable couples the drum and the curtain; and the curtain is opened in response to the winding of the cable about the drum in response to drum rotation.

A drum drive mechanism is axially aligned relative the axis of the drum so that both components extend completely across the frame or shell immediately adjacent the folded curtain.

Upon occurrence of (l) a manual switch operation to effect damper closure, (2) a power failure, (3) circuit malfunctioning, or (4) the detection of an undesired condition such as smoke or fire, the drum drive clutch is disengaged. When the clutch is disengaged, the drum unwinds to lower the curtain and close the damper.

In an alternative drum embodiment, the drum includes a cable takeup spool and a drum body of relatively greater mass than the spool. A drawn cup roller clutch couples the spool to the drum body. This clutch is engaged when the curtain is folded to open the damper; and the clutch is disengaged when the curtain is released to close the damper. With this drum arrangement the forces of drum momentum acting upon the cable (and tending to rewind the cable in the opposite direction) are substantially minimized when the curtain is released for damper closure.

9 Claims, 19 Drawing Figures PATENTEUMAR 7 I972 3,646,877

SHEET 5 OF 5 David H. Ell/'5 ATTORNEY CLOSURE orsnnon BACKGROUND OF THE INVENTION In recent years an increased emphasis has been placed upon the need for improved safety devices to minimize the loss of life and property occurring from the products of combustion. The prevalence of large buildings with air-conditioning and ventilating ducts through walls requires the installation of dampers in these openings to isolate an unsafe building area from the remaining areas in the event of a hazardous condition. These dampers must close quickly and reliably in the event of a fire, otherwise the products of combustion will travel through the damper containing ducts or firewalls. Additionally, the dampers should preferably be capable of restoration to an operate condition without extensive manual servicing occasioned by the necessary replacement of components, such as fusible links, or the rearming of the detection system by reengagin g various linkages.

The damper control system should also be fail-safe in the sense that a power failure, or other circuit malfunction in the undesired-condition detecting system, will automatically close the damper. Additionally, upon restoration of power, or correction of the circuit malfunction, the damper must be operated without the necessity for a service man to obtain access to the damper to replace or rearm components.

DESCRIPTION OF THE PRIOR ART Almost invariably damper control devices of the prior art have employed fusible links. The melting of these links effects damper closure by activating a closer mechanism. The use of fusible links is generally unsatisfactory due to the delay involved in melting the link which enables the products of combustion to spread. Additionally, such systems are not fail-safe; and they require manual replacement of each link before the dampers are readied for further operation.

Examples of fusible link systems are shown in US. Pat. Nos. 3,467,163, 3,337,99l and 3,273,632.

Other remotely related patents have described louver, vane, or door positioncrs. The controls for these devices have in some instances dispensed with fusible links, but in most instances the systems are either not failsafe, or alternatively, upon occurrence of an undesired condition, manual restoration of the system is required.

Examples of these systems appear in US. Pat. Nos. 3.249,!48, 3,219,104, 3,207,273, 3,177,367, 3,164,404 and 2,980,970.

SUMMARY OF THE INVENTION The closure operator of this invention features a drum drive housing and a drum, both mounted within the damper frame. In a preferred embodiment, the drive motor is remotely located from the drum drive housing to minimize the obstruction to airflow through the damper. The damper and operator may be located in a duct or firewall which is remote and difficult to service.

Inasmuch as a fusible link is eliminated, and a quickly responsive fire or smoke detector, such as a photocell or ionization-type sensor, is employed, damper closure is effected immediately. A manual switch remotely located can also open or close the damper as required.

In the event of a power failure, or detector malfunctioning, the damper automatically closes. Upon correction of these conditions, the damper is automatically restored to the desired position.

The structure for attaining these functions is briefly described in the abstract.

DETAILED DESCRIPTION OF THE DRAWINGS In order that all of the structural features for attaining the objects of this invention may be readily understood, reference is herein made to the following drawings where:

FIG. I is a perspective view showing the closure operator of this invention applied to a multifold curtain damper with the individual folds shown in the damper closed position;

FIG. 2 is a sectional view taken along line 22 of FIG. I with the modification, however, that the curtain has been folded to the damper open position;

FIG. 3 is a sectional view showing the internal construction of the drum drive mechanism and the coupled drum,

FIG. 4 is a sectional view of the drum drive mechanism taken along line 44 of FIG. 3;

FIG. 5 is a perspective view of the driven clutch member which is coupled to the drum;

FIG. 6 is an exploded view including the driving clutch member and the fork assembly for driving the two clutch elements into engagement;

FIG. 7 is a view of the motor drive assembly with the housing partially broken away so as to shown the internally housed drive motor and the reduction gear;

FIG. 8 is an end view of the flexible shaft adapter of the motor drive mechanism;

FIG. 9 is a sectional view taken along line 99 of FIG. 8 and showing the internal construction of the flexible shaft adapter,

FIG. I0 is a schematic circuit diagram showing the connection of the drive motor and the solenoid-armature actuated clutch to a condition detector (smoke or heat, for example) to effect fail-safe operation of the damper;

FIG. II is a partial sectional view of a second embodiment of a drum drive mechanism employing an electromagnetic clutch and coupled to a drum;

FIG. I2 is a sectional view taken along line 12-l2 of FIG. II and showing the driving clutch member and its attached gear;

FIG. I3 is a sectional view taken along line I3I3 of FIG. I2 showing particularly the grooved web connecting the adjacent slot ends of the driving clutch member;

FIG. 14 is a sectional view taken along line 14-44 of FIG. 11 showing the driven clutch member;

FIG. 15 is a partial section of a second drum embodiment incorporating an integral drum clutch designed to minimize the adverse effects of excessive drum momentum during abrupt curtain closure;

FIG. I6 is a partial sectional view taken along line 16-16 of FIG. 15 and showing the drum clutch engaged;

FIG. I7 is a partial sectional view taken along line l7-I7 of FIG. 15 and showing the drum clutch disengaged;

FIG. I8 is a full sectional view taken along line 18-18 of FIG. 15 and showing the cable anchor coupled to the drum; and

FIG. I9 is a perspective view of the cable anchor.

DETAILED DESCRIPTION OF THE FIRST PREFERRED EMBODIMENT Referring now to FIG. I, the opening and closing of multifold curtain damper l is controlled by a closure operator the main components of which include motor assembly 2, drum drive mechanism 3, flexible shaft 4 which transmits the motor shaft output from assembly 2 to gearing mechanism (FIG. 3) located within drurn driven mechanism 3, drum 5 which is rotated by drum drive mechanism 3, and limit microswitch 6.

Drum 5 supports cable anchor 7 (FIG. 3) to which cable 8 is tied. Cable 8 passes over cable pulleys 9, I0 and 11 with the terminal ends 12 and 13 of cable 8 being tied to curtain lift tray I4.

Multifold curtain damper I is of conventional construction in which curtain I5 is formed from a plurality of sheet metal folds. Curtain I5 is enveloped or housed within frame or shell I6 which includes top 17, bottom 18 and sides 19 and 20.

Curtain guide channel 2] is fixed to the inside surfaces of bottom 18 and sides 19 and 20 so that possible lateral movements of curtain I5 are constrained.

It should be noted, that while the damper operator of this invention is shown applied to a continuous multifold curtain, the operator is nonetheless applicable to that type of damper employing continuous interlocking slats or blades which form a folding curtain of the type shown in U.S. Pat. Nos. 3,327,764 and 3,273,632, for example. In the designs of the cited patents, the curtains are formed of interlocking sections which are hinged relative one another. Notwithstanding the structural curtain differences as compared to the continuous sheet metal curtain shown in FIG. I, the closure operator of this invention may be advantageously employed therewith.

FIG. 2 is a sectional view taken along line 2-2 of FIG. I with the modification, however, that the curtain has been folded to the damper open position. Drum 5 has been rotated in a counterclockwise direction by drum drive mechanism 3 so that cable 8 is wound upon the drum, until such time as normally closed limit microswitch 6 is actuated by top fold a of curtain I5 so as to open this switch. As is hereafter set forth, particularly with reference to the schematic circuit diagram of FIG. [0, the opening of limit switch 6 deenergizes the motor within motor assembly 2 so that rotation of drum 5 is immediately ceased.

As is shown in FIG. 2, drum drive mechanism 3 and drum 5 are located immediately behind the folded curtain I5 when the damper is open. With this disposition of components, the damper operator structure does not serve to obstruct the passage of air through the damper. Consequently, the efficiency of the damper in transmitting maximum air volume is not reduced by installing the damper drive mechanism and drum within the frame or shell 16.

FIGS. 3 through 6 show a first preferred embodiment of drum drive mechanism 3. FIG. 3 additionally shows the coupling of drum 5 to the drum drive shaft 25 which is an integral part of driven clutch coupling 26.

In general, drum drive mechanism 3 includes a worm 27 which is driven by a flexible shaft 4 (not shown in FIGS. 3 through 6). Worm 27 is permanently engaged to drive wheel gear 28 in response to rotating torque supplied by flexible shaft 4.

Wheel gear 28 is formed with three holes 35 (FIG. 4) which receive mating pins 36 (FIG. 3), which pins are rigidly fixed to clutch driving disc 37. Three coil springs 38 (FIG. 3) are individually carried upon a pin 36 and sandwiched between wheel gear 28 and clutch driving disc 37 as is shown in FIG. 3.

The forces exerted by springs 38 drive clutch driving disc 37 to the left so that pins 36 in the usual instance do not protrude into the cavities 39 formed in driven clutch coupling 26 by means of outer ring 40, inner ring 4t and the three connecting vanes 42 (FIG. 5).

Accordingly, with pins 36 disengaged from driven clutch coupling 26, rotation of worm 27 cannot produce a corresponding rotation ofdrum 5 so as to wind or unwind cable 8 relative drum 5.

The engagement of clutch driving disc 37 and driven clutch coupling 26 is effected by a movement of clutch actuating plate 45 to the right (FIGS. 3 and 6).

Clutch actuating plate 45 is formed with a central hole 46 and a pair of pivot arms 47.

As is shown in FIGS. 3 and 6, pivot arms 47 are pivotally coupled to adjacent engaging arms 48 which are an integral part of two branch fork 49.

The lower terminal ends of fork 49 are formed with holes 50 (FIG. 6) which pivot on shaft 5] (FIG. 4). Shaft 51 is supported on a pair of brackets 52 which are carried by rear housing section 53 ofdrum drive mechanism 3.

The upper terminal ends of fork 49 are formed with holes 60 (FIG. 6) which receive shaft 61 (FIG. 4).

Shaft 61 pivotally supports the left terminal end (FIG. 3) of cross-shaped magnetizable armature 62. The horizontal arm of armature 62 reciprocates within the bore of a solenoid 63. In the event that solenoid 63 is energized, as will be hereinafter outlined, armature 62 is drawn to the right (FIG. 3); thus the upper terminal ends of fork 49 are also drawn to the right, causing clutch actuating plate 45 to pivot about shaft St.

The rightward movement of clutch actuating plate 45 forces clutch driving disc 37 to the right, thus compressing the three springs 38 and enabling pins 36 to be received within cavities 39 located within driven clutch coupling 26.

With this pin engagement, the clutch is engaged, thus rotation of worm 27 in turn rotates wheel gear 28 which in turn drives shaft 25 to rotate drum 5 responsively.

Rear housing section 53 fixedly supports stepped shaft 75, this shaft in turn carries clutch actuating plate 45, clutch driving disc 37 and wheel gear 28 so that all of these latter elements are enabled to move relative the shaft. In particular. clutch actuating plate 45 reciprocates back and forth in response to the energization of solenoid 63; and clutch driving disc 37 and wheel gear 28 rotate relative to shaft 75 in response to torque applied by worm 27. Washer and snap ring 64 retain gear 28 and the associated components on stepped shaft 75.

Driven clutch coupling 26 is rotatably supported relative front housing section 65 by means of bearing 66 (FIG. 3). Snap ring 67 retains clutch coupling 26 relative to front housing section 65. Housing sections 53 and 65 are joined by means of bolts 68 and 69 (FIG. 3) which engage threaded bosses formed in housing sections 53 and 65.

The right terminal end of drum 5 receives a plastic bearing 70 which is carried by a supporting pin 7]. Pin 71 is integrally attached to a circular flange 72 which is screwed to the right side 20 offrame I6 (FIG. I).

Drum drive shaft 25 is formed with a plurality of flats 73 which are received tightly by left end wall 74 of drum 5 (FIG. 3) so that rotation of drum drive shaft 25 rotates drum 5.

FIGS. 7 through 9 show motor assembly 2 and details of the flexible shaft adapter 80. Motor assembly 2 includes an alternating-current motor BI whose output is coupled to reduction gear 82. The output of the reduction gear is in turn coupled to socket 83 of adapter 80. Socket 83 is formed with a keyway 84 which is adapted to receive a male tip connected to the flexible core (not shown) offlexible shaft 4.

Socket 83 rotates relative to threaded adapter sleeve 85 on plastic bearing 86. Housing 87 contains motor 81 and reduction gear 82, and also provides support for flexible shaft adapter 80.

The schematic circuit of FIG. I0 shows the electrical connection of solenoid 63, limit microswitch 6, and motor 8I to effect opening and closing of multifold curtain damper I in a fail-safe manner of operation.

Additionally, the schematic circuitry incorporates a condition responsive detector and an amplifier unit 90 which is failsafe in operation. In particular, if all of the components of detector and amplifier circuitry 90 are properly operative, damper I will open upon manual closure of switch 9I. If, however, detector and amplifier unit 90 is not properly operative, or alternatively, the detector senses a condition such as flame or smoke, damper curtain I5 will close if opened or will remain closed if in a closed position relative the damper frame.

The detailed operation of the circuitry of FIG. I0 is as follows:

Assuming detector and amplifier unit 90 is in proper operating condition and that the detector (not shown) input at terminals 92 and 93 indicates an absence of a flame or smoke condition, damper I may be opened or closed in response to the manual operation of switch 9!. That is, closure of switch 91 applies line voltage from terminals 94 and 95 to amplifier A of detector and amplifier unit 90. The application of line voltage to amplifier A energizes amplifier output relay 96, thereby closing normally open contact 96a.

The closure of contact 960 applies line voltage to the winding of power relay 97. With this occurrence, normally open contact 970 is closed thereby applying line voltage to energize solenoid 63 and also to energize motor 81 through normally closed microswitch 6.

The energization of solenoid 63 causes armature 62 to pivot fork 49 so that clutch actuating plate 45 forces clutch driving disc 37 to the right (FIG. 3), thereby causing pins 36 to engage cavities 39 of driven clutch coupling 26. With this clutch engagement. the rotation of worm 27 in response to the energization of motor 81 causes corresponding rotation in wheel gear 28 to drive drum 5 in such a direction as to elevate curtain to the position shown in FIG. 2.

When top fold 150 (FIG. 2) contacts limit microswitch 6 so as to open this switch, motor 81 is deenergized thus holding the damper curtain 15 in the position shown in FIG. 2.

It should be noted that solenoid 63 is continuously energized during the period that curtain 15 is in the opened position shown in FIG. 2, and thus, the drum is unable to lower the curtain in opposition to the holding force exerted by worm 27.

In the event of power failure appearing at terminals 94 or 95, or alternatively, a malfunctioning in amplifier unit A, or the detection of an undesired condition at input terminals 92 or 93, the otherwise closed contact 96a is released, thereby deenergizing power relay 97 which in turn releases contact 970.

When contact 97a is released, solenoid 63 is deenergized thereby disengaging the clutch elements and enabling the curtain to drop immediately to the closed position shown in FIG. 1.

DETAILED DESCRIPTION OF THE SECOND PREFERRED EMBODIMENT Referring now to FIGS. 11 through 14, an alternative drum drive mechanism 100 is shown which performs substantially the same function as drum drive mechanism 3 previously described with reference to FIGS. 1 through 6. Drum drive mechanism 100, however, employs an electromagnetic clutch to transmit the rotating torque applied to worm 101 to drum I02. Worm 10] corresponds in function and connection to worm 27 previously described; and drum I02 corresponds in construction and function generally to drum 5 previously described.

Worm 101 engages worm ring gear 103 which is rigidly fixed to a projecting lip 104 of driving clutch member 105 by a plurality of circularly disposed machine screws 106. Additionally, worm ring gear 103 is seated upon and carried by an annular projecting lip 107 which is part of driving clutch member 105.

Driving clutch member 105 is also formed with a second projecting lip 108 which projects in the opposite axial direction with respect to projecting lip 107v Driving clutch member 105 also includes a radial section 109 which is formed with four outer circular slots 110 (FIG. 12) and also four inner circular slots 11 I.

The adjacent ends of outer circular slots 110 are joined together by a plurality of webs 112 (FIG. 13); and the adjacent ends of inner circular slots 111 are joined together by a plurality of grooved webs 113.

The innermost end of radial section 109 is integrally joined to an annular ring 114 (FIG. 11) which is supported upon rotatable shaft 115 by needle bearings 116.

Driven clutch member 120 includes a radial section 121 which is in normal light friction contact with the adjacent sur face of radial section 109 of driving clutch member 105; The spacing of these radial sections as shown in the drawings of FIG. 11 is greatly exaggerated so that the distinctive parts may be seen.

As is shown in FIG. 14, driven clutch member 120 is formed with a plurality of circular slots 122 the adjacent ends of which are joined together by means of grooved webs 123 which correspond generally to grooved webs 112 and 113 shown in cross section in FIG. 13.

Drive clutch member 120 is formed with a central hole 125 the periphery of which includes two key slots 126. Key slots 126 extend for the entire axial portion of annular ring 127 of driven clutch member 120.

Driven clutch member 120 is locked to shaft by a pair of woodward keys 128. In view of the fact that key slots 126 are elongated, driven clutch member is capable of limited reciprocating movement along the longitudinal axis of shaft 115.

Driven clutch member 20 is limited in its movement on shaft 115 by washer I29 and snap retaining ring 130.

The left terminal end of shaft 115 is supported relative housing section 131 by a plurality of needle bearings 132; the right terminal end of rotatable shaft 115 is supported relative housing section 133 by means of plastic spool bearing 134. Plastic spool bearing 134 engages annular ring shoulder 135 of housing section 133.

Annular shoulder 135 supports circular magnetic core 136 which is U-shaped in cross section. Electrical coil 137 is housed within the outer pole ring 138 and the inner pole ring 139 of magnetic core 136.

Magnetic core 136, driving clutch member 105, and driven clutch member 120 are all fabricated of magnetizable materials. Housing sections 131 and 133 are preferably fabricated of non-magnetizable material, such as aluminum, so as not to influence adversely the magnetic fields generated by coil 137.

In the event that coil 137 is energized by a direct-current voltage, circular magnetic core 136 is magnetized with lines of flux emanating and terminating at pole rings 138 and 139. In view of the fact that slots 110 and III are formed in driving clutch member 105 and ofi'set slots 122 are formed in driven clutch member 120, the lines of flux will follow generally the curved path 140 shown in FIG. 11. It will thus be seen that the flux lines 140 traverse the slight air gap between clutch members 105 and 120 four times. This path of flux travel causes firm friction engagement of driven clutch member 120 to driving clutch member 105. Accordingly, when worm 101 is turning ring gear 103, shaft IIS rotates to produce a corresponding rotation in drum 102.

Thus, the alternative drum drive mechanism 100 shown in FIGS. 11 through 13 is operative to perform essentially the same functions as drum drive mechanism 3 shown in FIGS. 1 through 6.

Drum drive mechanism 100 is driven by a motor assembly and a flexible shaft which is identical to components 2 and 4 previously described. Corrcspondingly, drum drive mechanism 100 is wired in a schematic circuit diagram which is substantially identical with that shown in FIG. 10 with the single exception that coil 137 of the electromagnetic clutch is substituted for solenoid 63 in FIG. 10. Moreover, inasmuch as the electromagnetic clutch of FIG. 11 operates more efficiently on direct-current voltage, a rectifier circuit should be included in the alternating-current lines connected to coil 137 so that a pulsating direct-current voltage is supplied to this coil.

DETAILED DESCRIPTION OF A SECOND PREFERRED EMBODIMENT OF THE DRUM When drum 5 of FIG. 1 and drum 102 of FIG. 11 are operated to release a folded curtain, the relatively heavy weight of the curtain employed particularly in large dampers causes the drum to unwind rapidly. In many cases, the resulting drum momentum tends to rewind the cable in the opposite direction. This action, if repeated many times, will ultimately cause the cable to break prematurely.

The drum modification shown in FIGS. [5 through 18 features a cable storage spool which is sandwiched between drum sections 151 and 152. Drum sections 151 and 152 are rigidly fixed relative one another by machine bolt 153 which couples center drum plugs 154 and 155 to one another.

A drawn cup roller clutch is pressed within the central bore of cable storage spool 150. The inner surface of the drawn cup roller clutch I60 engages spindle shank 161 which is part of machine bolt I53.

Drawn cup roller clutch 160 cooperates with cable storage spool I50 and drum sections 151 and 152 in such a manner that when cable 8 of FIG. I, for example, is wound upon the drum so as to open the damper by folding the curtain l5, spool I50 is rigidly fixed relative drum sections 151 and 152 inasmuch as clutch I60 is engaged.

However, when the drum is released to permit lowering of the curtain, clutch I60 is overrun so that cable storage spool 150 is enabled to unwind freely of drum sections 151 and I52. Accordingly, in view of the fact that spool I50 generates considerably less momentum than the entire drum, which includes the spool and also drum sections I51 and I52, the tendency for the drum to overrun is eliminated, thus greater cable life is insured.

The sectional view of FIG. 16 shows the drawn cup roller clutch in the engaged position; and the sectional view of FIG. I7 shows the drawn cup roller clutch in the overrun position.

Referring to FIG. I6, which is illustrative of the position of the clutch components when the drum is elevating the curtain, spindle I61 and spool IIS rotate counterclockwise with the same angular velocity. Accordingly, needle bearings 162 which are positioned by the integral retainer springs 165 advance into locked positions on ramps I64, thereby causing the entire unit comprising shaft 161 and spool 150 to rotate in unison. Spring blocks I63 hold the springs I65 against needle bearings I62.

In FIG. 17, spool I50 because ofits lesser inertia than drum sections ISI and 152 rotates substantially faster than shaft 161. Accordingly, bearings I62 rotate in a counterclockwise manner by disengaging from ramp sections 164 thus permitting low friction overrunning.

Because of effective disengagement of cable storage spool I50 from drum sections 151 and I52 when curtain I is lowered, the momentum or inertia which tends to rewind the cable on the drum is eliminated.

In FIGS. 18 and I9, cable 8 is shown tied to spring anchor I66. Anchor 166 is split at I69 (FIG. I9) immediately adjacent mounting legs I68. Mounting legs 168 are inserted within friction engaging holes in spool [50; and anchor I66 is supported on stud 167 with the end of the anchor inserted within spool recess 170 (FIG. 18).

The Torrington Company, Bearings Division, Torrington, Connecticut, is currently marketing a drawn cup roller clutch which is satisfactory to perform the functions as clutch I60 shown in FIGS. IS through 18.

What is claimed is:

I. An operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capable of opening and closing an air passage defined by the frame or shell, comprising a rotatable drum positioned in the air passage within the frame or shell adjacent the curtain with the drum masked by the curtain when the curtain is folded so that the drum will not further obstruct airflow through the damper when the damper is opened beyond the air obstruction provided by the folded curtain, a cable coupling the drum and the curtain with the curtain being folded in response to winding of the cable about the drum in response to drum rotation, and a drum drive mechanism positioned in the air passage within the frame or shell adjacent the curtain with the drum drive mechanism masked by the curtain when the curtain is folded so that the drum drive mechanism will not further obstruct air flow through the damper when the damper is opened beyond the air obstruction provided by the folded curtain and with the drum drive mechanism being coupled to the drum to rotate the drum.

2. The combination of claim 1 in which the drum drive mechanism includes a clutch which is operatively engaged to fold the curtain and thus open the damper air passage by winding the cable about the drum relatively slowly. and in which the clutch is disengaged to enable at least a portion of the drum upon which the cable is wound to unwind relatively quickly and thus close the damper air passage.

3. An operator for a mullifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capable of opening and closing an air passage defined by the frame or shell, comprising a rotatable drum positioned within the frame or shell adjacent the curtain when the curtain is folded so that the drum will not obstruct air flow through the damper when the damper is opened, the drum including a cable takeup spool and a drum body of relatively greater mass than the spool, a cable coupling the drum and the curtain with the curtain being opened in response to winding of the cable about the drum in response to drum rotation, a drum drive mechanism positioned within the frame or shell adjacent the curtain when the curtain is folded so that the drum drive mechanism will not obstruct airflow through the damper when the damper is opened and with the drum drive mechanism being coupled to the drum to rotate the drum, the drum drive mechanism including a clutch which is operatively engaged to fold the curtain and thus open the damper air passage by winding the cable about the drum, the clutch being disengaged to enable at least a portion of the drum to unwind and thus close the damper air passage, and a second clutch coupling the spool to the drum body with the second clutch being engaged when the curtain is being folded to open the damper and the second clutch being disengaged when the curtain is released to close the damper whereby the forces of drum momentum acting upon the cable are substantially minimized when the curtain is released for damper closure.

4. An operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capable of opening and closing an air passage defined by the frame or shell, comprising a rotatably supported drum mounted relative to the frame or shell, a cable coupling the drum and the curtain with the curtain being folded in response to winding of the cable about the drum in response to drum rotation, a drum drive mechanism including a clutch which is operatively engaged to fold the curtain and thus open the damper air passage by winding the cable about the drum, and in which the clutch is disengaged to enable at least a portion of the drum to unwind and thus close the damper air passage, a motor coupled to the drum drive mechanism, means to deenergize the motor after the curtain is folded to open the damper, and means to maintain the clutch engaged when the motor is deenergized until damper closure is desired whereupon clutch disengagement enables at least a portion of the drum to unwind thus closing the damper.

5. The combination of claim 4 in which the motor is remote- Iy located from the drum drive mechanism, and a flexible shaft transmits motor shaft output to the drum drive mechanism.

6. The combination ofclaim 4 in which the clutch is an electromagnetic clutch which includes a drum drive shaft coupled to the drum, an electromagnet, driving and driven magnetizable clutch plates enveloping the shaft and in which the driving clutch plate is geared to the motor shaft output and the driven clutch plate is keyed to the drum drive shaft, whereupon energization of the electromagnet causes the two clutch plates to engage one another to cause the motor to rotate the drum.

7. The combination of claim 6 in which a worm ring gear is fixed to the driving clutch plate, and a worm gear driven by the motor engages the worm ring gear.

8. In an operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capable of opening and closing an air passage defined by the frame or shell in response to the rotation of a drum which is coupled to the curtain by means of a cable, the improvement comprising the drum including a cable takeup element and a drum body of relatively greater mass than the takeup element, and a clutch coupling the takeup element to the drum body with the clutch being engaged when the curtain is being folded to open the damper by rotating the entire drum in a cable winding direction, and the clutch being disengaged when the curtain is released to close the damper whereby the forces of drum momentum acting upon the cable by the drum body rotating in the cable unwind direction are substantially minimized when the curtain is released for damper closure.

9. In an operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the gaged when the curtain is released to close the damper whereby the forces of drum momentum acting upon the cable are substantially minimized when the curtain is released for damper closure, and in which the cable takeup element is a spool sandwiched between the drum body which is formed into two sectionsjoined by a shaft which carries the clutch and spool 1 l O i 

1. An operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capabLe of opening and closing an air passage defined by the frame or shell, comprising a rotatable drum positioned in the air passage within the frame or shell adjacent the curtain with the drum masked by the curtain when the curtain is folded so that the drum will not further obstruct airflow through the damper when the damper is opened beyond the air obstruction provided by the folded curtain, a cable coupling the drum and the curtain with the curtain being folded in response to winding of the cable about the drum in response to drum rotation, and a drum drive mechanism positioned in the air passage within the frame or shell adjacent the curtain with the drum drive mechanism masked by the curtain when the curtain is folded so that the drum drive mechanism will not further obstruct air flow through the damper when the damper is opened beyond the air obstruction provided by the folded curtain and with the drum drive mechanism being coupled to the drum to rotate the drum.
 2. The combination of claim 1 in which the drum drive mechanism includes a clutch which is operatively engaged to fold the curtain and thus open the damper air passage by winding the cable about the drum relatively slowly, and in which the clutch is disengaged to enable at least a portion of the drum upon which the cable is wound to unwind relatively quickly and thus close the damper air passage.
 3. An operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capable of opening and closing an air passage defined by the frame or shell, comprising a rotatable drum positioned within the frame or shell adjacent the curtain when the curtain is folded so that the drum will not obstruct air flow through the damper when the damper is opened, the drum including a cable takeup spool and a drum body of relatively greater mass than the spool, a cable coupling the drum and the curtain with the curtain being opened in response to winding of the cable about the drum in response to drum rotation, a drum drive mechanism positioned within the frame or shell adjacent the curtain when the curtain is folded so that the drum drive mechanism will not obstruct airflow through the damper when the damper is opened and with the drum drive mechanism being coupled to the drum to rotate the drum, the drum drive mechanism including a clutch which is operatively engaged to fold the curtain and thus open the damper air passage by winding the cable about the drum, the clutch being disengaged to enable at least a portion of the drum to unwind and thus close the damper air passage, and a second clutch coupling the spool to the drum body with the second clutch being engaged when the curtain is being folded to open the damper and the second clutch being disengaged when the curtain is released to close the damper whereby the forces of drum momentum acting upon the cable are substantially minimized when the curtain is released for damper closure.
 4. An operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capable of opening and closing an air passage defined by the frame or shell, comprising a rotatably supported drum mounted relative to the frame or shell, a cable coupling the drum and the curtain with the curtain being folded in response to winding of the cable about the drum in response to drum rotation, a drum drive mechanism including a clutch which is operatively engaged to fold the curtain and thus open the damper air passage by winding the cable about the drum, and in which the clutch is disengaged to enable at least a portion of the drum to unwind and thus close the damper air passage, a motor coupled to the drum drive mechanism, means to deenergize the motor after the curtain is folded to open the damper, and means to maintain the clutch engaged when the motor is deenergized until damper closure is desired whereupon clutch disengagement enables at least a portion of the drum to unwind thus closing the dAmper.
 5. The combination of claim 4 in which the motor is remotely located from the drum drive mechanism, and a flexible shaft transmits motor shaft output to the drum drive mechanism.
 6. The combination of claim 4 in which the clutch is an electromagnetic clutch which includes a drum drive shaft coupled to the drum, an electromagnet, driving and driven magnetizable clutch plates enveloping the shaft and in which the driving clutch plate is geared to the motor shaft output and the driven clutch plate is keyed to the drum drive shaft, whereupon energization of the electromagnet causes the two clutch plates to engage one another to cause the motor to rotate the drum.
 7. The combination of claim 6 in which a worm ring gear is fixed to the driving clutch plate, and a worm gear driven by the motor engages the worm ring gear.
 8. In an operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capable of opening and closing an air passage defined by the frame or shell in response to the rotation of a drum which is coupled to the curtain by means of a cable, the improvement comprising the drum including a cable takeup element and a drum body of relatively greater mass than the takeup element, and a clutch coupling the takeup element to the drum body with the clutch being engaged when the curtain is being folded to open the damper by rotating the entire drum in a cable winding direction, and the clutch being disengaged when the curtain is released to close the damper whereby the forces of drum momentum acting upon the cable by the drum body rotating in the cable unwind direction are substantially minimized when the curtain is released for damper closure.
 9. In an operator for a multifold curtain damper having a frame or shell enveloping the damper curtain and in which the curtain is capable of opening and closing a passage defined by the frame or shell in response to the rotation of a drum which is coupled to the curtain by means of a cable, the improvement comprising the drum including a cable takeup element and a drum body of relatively greater mass than the takeup element, and a clutch coupling the takeup element to the drum body with the clutch being engaged when the curtain is being folded to open the damper and the clutch being disengaged when the curtain is released to close the damper whereby the forces of drum momentum acting upon the cable are substantially minimized when the curtain is released for damper closure, and in which the cable takeup element is a spool sandwiched between the drum body which is formed into two sections joined by a shaft which carries the clutch and spool. 